Evaluation of volumetric and mechanistic properties of asphalt mixtures: laboratory vs. field

Abstract

The maintenance and growth of the United States infrastructure is vital to the economic, social, and cultural success of the country. For this reason significant resources must be allocated to ensure adequate paving mixtures are designed, produced, and constructed. A critical issue that has received considerable attention in recent years is to identify and quantify causes, sources, and levels of variability in volumetric and mechanical properties of the mixture. This requires evaluation of three possible scenarios for production of asphalt mixture specimens: (1) laboratory mixed and laboratory compacted specimens (LL), (2) plant mixed and laboratory compacted specimens (PL), and (3) plant mixed and field compacted specimens (PF). The objective of this project was to quantify sources and causes of variability in the measurements of volumetric and mechanical properties of dense-graded asphalt mixtures for three types of specimens. This was accomplished by collecting and reviewing published and unpublished national information on studies conducted to evaluate the variability of volumetric and mechanical properties of asphalt mixtures, and current practices adopted by the states to incorporate variability in the specifications. The researcher surveyed highway agencies and contractors that may have been able to provide data. Statistical analyses, including a metaanalysis were conducted based on the collected data. This research reports levels of variability for a wide range of volumetric and mechanical properties. Also, the levels of variability were comparable for various state departments of transportations (DOTs) located in different climatic regions. Additionally, nominal maximum aggregate size (NMS) of asphalt mixtures appears to influence the levels of variability observed for the various volumetric and mechanical properties. This report finds additional research is required to determine the cause of the variation between the three sample types with respect to process-based factors.